Straightening machines have been proposed including those operating on a planetary principle. One straightening machine for poppet valves included two rotary dies of similar diameter with spaced axes and slightly different peripheral speeds engaging the stem of the poppet valve so that the workpiece passed between the nip of the die rollers. One die roller had a straightening disc freely journalled coaxially thereon to engage the underside of the head of the poppet valve as the valve gradually passed through the nip. Any wobble to the head of the poppet valve was removed by engagement with the free running straightening disc. Such prior art machine had the difficulty of not being able to satisfactorily control the attitude of the workpiece because of the limited area of contact of the workpiece stem with the two separated roller dies, both of which have convex faces. The poppet valve stem would easily become cocked at an angle other than parallel to the two roller dies, especially because of the unbalanced force caused by the straightening disc cyclically engaging the poppet valve head. The problem to be solved then is how to establish a flanged stem workpiece straightening machine to overcome this deficiency.
An object of the invention is to provide a straightening machine for flanged stem workpieces wherein the workpiece is securely held during travel through the machine.
Another object of the invention is to provide a straightening machine wherein a flange of a stemmed workpiece is cyclically bent more and more to a midpoint of a die and is then bent in decreasing amounts until the flange is straight, namely, perpendicular to the stem.
Another object of the invention is to provide a straightening machine wherein the flange of the stemmed workpiece moves in a first path and a straightening roller moves in a second path intersecting the first path so as to engage and bend the workpiece.
Another object of the invention is to provide a straightening machine wherein the phase position of a straightening roller relative to a workpiece flange is gradually changed so that the straightening roller engages and straightens the workpiece flange.
Other objects and a fuller understanding of this invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings, in which: